Certain substituted 1,3,2,4-diazadiphosphetidines are well-known for their unique structural, bonding and coordination properties.
Michaelis and Schroeter first reported the synthesis of selected 1,3,2,4-diazadiphosphetidines in Ber. 27, 490 (1894). Further detailed syntheses of such compounds have been reported by R. R. Holmes et at., Inorg. Chem. 2, 380 (1963); E. W. Abel et al., J. Chem. Soc. 1965, 57; O. J. Scherer et al., Angew. Chem., Inter. Ed., 8,752 (1969); and W. Zeiss et at., Z. Naturforsch., 32b, 485 (1977). The elucidation of a crystal structure was first reported by K. W. Muir et al., J. Chem. Soc., Chem. Comm., 1971, 1405; and later by R. Keat et at., J. Chem. Soc., Chem. Comm. 1978, 372 and M. L. Thompson et al., J. Am. Chem. Soc., 103, 6770 ( 1981 ).
The use of certain diphenylamine substituted 1,3,2,4-diazadiphosphetidines as high temperature (300.degree.-450.degree. C.) stabilizers for polyimides and polybenzoxazoles is reported in Vysokomol Soedin., Ser. A, 20(1), 207 (1978). The use of selected 1,3,2,4-diazadiphosphetidines as light stabilizers for cellulose acetate fibers and films is reported in USSR Otkrytiya, Izobret. Prom. Obraztsy, Tovarnye Znaki, 53(20), 84 (1976) [=Soviet Union 515,843; Derwent 64543Y/36; C.A. 85 (14), 95681q]. In the same journal at 54(33), 209 (1976)[=Soviet Union 441,806; Derwent 54865A/30; C.A. 87 (26), 202623n], the use of 1,3-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionamido)-2,4-bis(3,5-di-tert -butyl-4-hydroxyphenylpropiohydrazido)-diphosphazane as a stabilizer for polyolefin is disclosed. Soviet Union 445,328 (Derwent 58226A/32) discloses that poly-3,3-bis(chloromethyl)-oxacyclobutane can be heat stabilized without discoloration by the addition of 1,3-di-(3,5-di-tert-butyl-4-hydroxyphenylpropipnamide)-2,4-(3,5-di-tert-bu tyl-4-hydroxyphenyl-propiohydrazino)-diphosph(III)azane. However, the instant 1,3,2,4-diazadiphosphetidines are structurally distinguished from each of the diazadiphosphetidine and diphosphazane stabilizers of these Russian references.